This invention relates to boarding platforms for transferring personnel between a fixed dock structure and a barge or the like. More particularly, this invention relates to a boarding platform which is capable of adjusting its vertical position to accommodate varying tidal conditions. Marine boarding platforms range from simple boarding platforms fixed to the dock structure to fairly elaborate arrangements fixed to both the vessel and the dock structure with complex mechanisms to permit the platform to accommodate for swells and for parallel and perpendicular drifting relative to the dock. Due to the unpredictable nature of bodies of water, and particularly the peculiarities of river and coastal waters, such prior art devices have not been entirely successful principally because of their lack of safety features and their lack of versatility. For example, a simple gangplank in use today presents the possibility of injury or equipment damage if a river swell causes the barge to rise contacting the gangplank. A further hazardous condition exists if the barge drifts parallel to or perpendicular to the dock and there may be possible damage or serious injury should a person fall between the vessel and the dock.